Wambou
I don't do quick races but I will try to answer your questions.
I used to chage engine every othe races, but now I can afford changing them every races. It depends if you have enough coins.
For tyres, I do 1 practice with super soft tyres, to confirm the setup, then I use the tyres I intend to use during the race.
I can check tyre wear and fuel consumption with that compound.
I also try to do that at race temperature, but it's not always possible to do so.
Have fun racing
Sorry, with Q's I meant qualifying, but I guess the game don't have them or just calls them practice.
I was asking about the engines because of the tokens, if you need to change them in every race then you have to buy tokens no matter what.